Patent application WO 2010/070012 A1 discloses a solution for ensuring the navigation integrity of a system using a GNSS receiver for executing close coupling hybridization. This solution is based on a bank of Kalman filters and the use of raw measurements supplied by the GNSS receiver, typically the pseudo-ranges between the receiver and each satellite of a constellation. The document “A new failure detection approach and its application to GPS autonomous integrity monitoring”, by Ren Da et al., IEEE transactions on aerospace and electronic systems, vol. 31, no. 1, Jan. 1, 1995, also has a similar approach.
This solution requires having access to all GNSS measurements. Some GNSS receivers do not allow access to these measurements (especially pseudo-ranges) and provide only the navigation solution of the receiver (position, speed, time).
This solution also has the drawback of needing a large number of Kalman filters (typically 12 for one constellation of satellites). Some inertial navigation systems have no sufficiently powerful processors to run such a battery of filters.
Finally, this solution takes into consideration only a single constellation of satellites, whereas some receivers exploit signals originating from satellites belonging to several constellations (GPS, Glonass, and soon Galileo, Compass . . . ).
There is a need for an alternative solution which can ensure the integrity of hybrid navigation of a multi-constellation loose coupling system and which can advantageously be executed by means of a limited number of Kalman filters to be implemented on processors of lesser capacity.